Probiotics are live microorganisms that can support human health. Prebiotics are compounds that feed probiotics.
In this article, we’ll look into the health benefits of prebiotics and probiotics. We’ll also describe where you can find them and whether there are any factors to consider before you start.
Difference between probiotics and prebiotics
Although there’s only one letter of difference between them, probiotics and prebiotics are not the same. Probiotics are live microbes that benefit your health when you consume them in adequate amounts.
You can find probiotics in supplements – which may be liquids, tablets or sachets.
You may have heard that fermented foods are ‘probiotic.’ Technically, this isn’t true: most fermented foods don’t contain probiotics.
But these foods often do contain live bacteria, and they may support your overall gut health, so we’ll delve into fermented foods later on.
Meanwhile, prebiotics are ‘food’ for your gut bacteria. Most prebiotics are fibre – more specifically, a type of fermentable fibre that’s rapidly broken down by bacteria in your gut.
Your digestive system can’t break down fibre, so it passes into your large intestine (colon), where most of your gut bacteria live. And your gut bacteria can eat fibre. In fact, ‘good’ gut bacteria thrive when there’s fibre around.
You can get prebiotic fibre through foods, drinks or supplements. Prebiotics naturally occur in many plants, including fruits, vegetables and whole grains.
Probiotics or prebiotics: Which should you take?
Prebiotics and probiotics are ‘synergistic’ – they work well together and enhance each others’ effects.
Because ‘good’ bacteria (probiotics) need fibre (prebiotics) to survive, having both together makes sense.
So, prebiotics feed probiotics. In theory, this helps support your gut microbiome by making sure that your ‘good’ gut bacteria thrive.
If you’d like to learn more about these fascinating relationships, we have an article on how your gut microbiome supports your overall health.
Where can you find probiotics?
Probiotics are widely available as supplements, which may be powders, liquids or capsules. But not all probiotics are equal.
If you're considering a probiotic supplement, make sure the label indicates that it contains live, active bacteria.
As we mentioned earlier, fermented foods don't usually contain probiotics. But they do often contain live microbes. The key difference is that there isn't research to show that these live microbes can improve our health. So, they’re not probiotic microbes.
Still, fermented foods are a great addition to your diet and may support your gut health. As most fermented foods are made from vegetables, they typically contain prebiotics, too.
Here are some examples of fermented foods:
- sauerkraut
- kimchi
- kombucha
- Greek or natural yoghurts
- some cheeses
For more examples and tips about what to buy, here’s an article on fermented foods.
Where can you find prebiotics?
Consuming fibre from whole plants is the simplest way to get prebiotics. All plants contain fibre, but those in the list below have especially high levels of prebiotic fibre:
- onions
- leeks
- bananas
- garlic
- asparagus
- Jerusalem artichokes
We also have some simple high-fibre recipes you can try.
Prebiotic supplements are widely available. But it’s generally better to take in fibre from whole foods. That way, you get the benefits of the plants’ other healthy compounds, like vitamins, minerals and polyphenols.
Also, there are many types of fibre, and different gut bacteria ‘prefer’ different types.
Plants naturally contain a range of fibres, while a prebiotic supplement usually contains just one type.
What are the benefits of probiotics?
Scientists are still investigating the health effects of probiotics and fermented foods. But there’s already mounting evidence that these products can boost our health.
Most scientific research into probiotics has explored their effects on people with certain health conditions. Specifically, research suggests that probiotics can help:
- support gut health
- reduce symptoms of irritable bowel syndrome (IBS)
- improve some forms of diarrhoea
- reduce bloating for some people
- help with respiratory infections, like the common cold
You can read more about the health benefits of probiotics here.
There’s also some evidence that fermented foods may support the health of your gut, immune system and metabolism.
Fermented foods can also:
- help with digestion by reducing any anti-nutrients and FODMAPs (a type of carbohydrate) in food
- improve your meal’s nutritional value by increasing levels of certain vitamins
- improve the texture and flavour of many dishes
What are the benefits of prebiotics?
The most commonly studied prebiotics are inulin, fructooligosaccharides, galactooligosaccharides and human milk oligosaccharides.
There’s been less research into prebiotics than probiotics, and scientists are still investigating whether prebiotic supplements offer health benefits.
However, there’s some evidence that prebiotics can influence your overall health and the makeup of your gut microbiome.
Prebiotic supplements may also increase the number of ‘good’ gut bacteria. These bacteria produce short-chain fatty acids, which support general health and fuel the cells that line your gut.
Meanwhile, there’s strong evidence that eating more fibre-rich plants can support your health.
Experts recommend that adults get 30 grams of fibre a day. But most of us in the United Kingdom don’t – on average, we consume just 20 g a day.
In fact, only 13% of males and 4% of females meet the 30-g target. It’s mostly because we don’t eat enough plants.
There’s good evidence that a fibre-rich diet can support:
So, adding more plants to your plate is likely to help keep you and your gut bacteria happy and healthy.
While there aren’t any official recommendations for prebiotics, some experts suggest that we get around 3–5 g per day.
Are there any risks linked to prebiotics or probiotics?
In general, probiotic and prebiotic supplements seem to be safe for most people.
But if you have any underlying health conditions, it’s best to chat with your doctor before you take a new supplement.
Humans have enjoyed fermented foods that contain live bacteria for a long, long time, so these foods are generally considered safe. But for people with IBS or other gut issues, they might worsen certain symptoms, like bloating.
Meanwhile, consuming prebiotic fibre from whole plants is considered safe for the vast majority of us.
But if your fibre intake is currently quite low, try to increase it gradually. This gives your gut time to adjust.
Summary
Probiotics are live bacteria, while prebiotics are food for bacteria. Both may benefit our gut health and overall health, but scientists are still working out the details.
Fermented foods are not technically probiotic, but they do contain live microbes and might help support gut health.
Probiotics and prebiotics are both available as supplements, though experts recommend that we get more dietary fibre – including prebiotic fibre – through food.
Experts consider prebiotics and probiotics to be safe for most people. But if you have an underlying health condition, speak with a doctor before you give them a try.
And if your fibre intake is currently low, try to add fibre to your diet slowly, so your gut has time to adjust.
To learn more about probiotics and other gut health topics, visit Symprove’s Gut Hub.
Sources
Dietary fibre and cardiovascular health: A review of current evidence and policy. Proceedings of the Nutrition Society. (2019). Link.
Dietary fibre from whole grains and their benefits on metabolic health. Nutrients. (2020). Link.
Effect of probiotics on common cold, influenza, and influenza-like illness. A systematic review and meta-analysis. Topics in Clinical Nutrition. (2023). Link.
Efficacy of probiotics in irritable bowel syndrome: Systematic review and meta-analysis. Gastroenterology. (2023). Link.
Fermented foods: Definitions and characteristics, impact on the gut microbiota and effects on gastrointestinal health and disease. Nutrients. (2019). Link.
Fibre. (n.d.). Link.
Health benefits and risks of fermented foods – the PIMENTO initiative. Frontiers in Nutrition. (2024). Link.
Investigating the influence of probiotics in preventing traveler's diarrhea: Meta-analysis based systematic review. Travel Medicine and Infectious Disease. (2024). Link.
Microbiota-dependent and -independent effects of dietary fibre on human health. British Journal of Pharmacology. (2019). Link.
Prebiotics. (n.d.). Link.
Prebiotics and probiotics in digestive health. Clinical Gastroenterology and Hepatology. (2019). Link.
Probiotics: Usefulness and safety. (2019). Link.
The health benefits of dietary fibre. Nutrients. (2020). Link.
The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology and Hepatology. (2014). Link.
Understanding prebiotics and fiber. (n.d.). Link.
Unveiling the role of functional foods with emphasis on prebiotics and probiotics in human health: A review. Journal of Functional Foods. (2024). Link.
